This invention relates to high voltage, gas-insulated bus equipment and more specifically relates to a novel arcing ring for the interior of the bus which is inexpensive and which will decrease the possibility that an interior arc in the bus will burn through the housing by causing the arc root to rapidly spin on the interior periphery of the arching ring.
High voltage gas-insulated bus and transmission lines (herein, the terms bus and transmission lines are used interchangeably) are well known in which a central conductor is centrally supported within the interior of a cylindrical grounded, gas-tight conductive housing or enclosure by spaced insulation supports. The insulation supports may be rods, disks, cones, or any other suitable structure. The interior of the housing is then filled with a suitable insulation gas, typically sulfur hexafluoride, under a given pressure such as three atmospheres. Bus of this type is used for transmission of power at voltages which, typically, may be 345 kV.
If, for some reason, there is a failure within the bus, a power arc may strike from the central conductor to the outer grounded housing. These arcs will move along the length of the housing until they reach a support insulator, and will remain at the insulator until the arc current is interrupted. To prevent the arc from burning through the relatively thin outer housing or enclosure, which conventionally is of aluminum, thick metal rings of arc-resistant material have been placed around the interior of the outer housing and adjacent the support insulator. An arrangement of this type is shown in German Pat. application No. 2,059,330, and DT-OS 2,307,195. These rings can withstand the standing arc root temperature without burn-through if they are sufficiently thick. In addition, the thick rings add resistance in the arc-current circuit. However, these rings are expensive, and require that the grounded housing have an increased diameter where they are located.
Other arrangements are known, for example, as shown in Swiss Pat. No. 541,215 for making the housing sections which might be exposed to arcing, of steel, rather than aluminum. Placing steel sections in an aluminum cylinder is expensive and can lead to corrosion at the joints, leading to the danger of gas leaks in the housing.
A description of the problem solved by the present invention is also given in U.S. Pat. No. 3,931,451 in which arc-resistant material is used for the housing section exposed to arcing.